For some applications, such as that of precision measuring instruments, it is necessary to form a continuous groove in and over a substantial portion of a surface of the instrument. Such a groove may be desired in those instances where a conductive paint or the like is to be applied to the bottom of the groove, which conductive paint is thereafter responsive to specific chemicals. When a reactive chemical contacts the painted line, the electrical continuity is disrupted, and an electric circuit is thereby opened to indicate the presence of such chemical. In the manufacture of chemical detectors, in which conductive paint or the like is applied to a surface, the use of grooves protects the paint, so that it the continuity is not inadvertently broken by scratching or physical abrasion, as is the case where the paint is applied to an exposed planar surface.
In such instruments, it is desirable to provide a conductive line which is arranged in serpentine-like manner, which has continuity between its ends, and which is formed in closely spaced grooves or the like in a surface of the member. For example, such grooves may be very fine indeed, and could for example be approximately 225 microns deep and approximately as wide, with the center of the grooves spaced apart approximately 375 microns, defining a land area between the adjacent edges of the grooves in the order of 175 microns.